Homework 3

Due Tuesday 27-Jan, at 9:00pm

To start

Create a folder named ‘hw3’
Download hw3.py to that folder
Edit hw3.py and modify the functions as required
When you have completed and fully tested hw3, submit hw3.py to Gradescope. For this hw, you may submit up to 15 times, but only your last submission counts.

Some important notes

This homework is individual. You are expected to write your own code and submit work that reflects your own understanding. You may discuss concepts with other students in the course, and you may use permitted resources, but you must follow the collaboration policy:
- Do not copy code from any source.
- If you look at code that you did not write, you must follow the 5-Minute Rule.
- You are responsible for protecting your own work so others cannot copy it. See the academic honesty policy for more details.
After you submit to Gradescope, make sure you check your score. If you aren’t sure how to do this, then ask a CA or Professor.
There is no partial credit on Gradescope testcases. Your Gradescope score is your Gradescope score.
Read the last bullet point again. Seriously, we won’t go back later and increase your Gradescope score for any reason. Even if you worked really hard and it was only a minor error…
Do not hardcode the test cases in your solutions.
The starter hw3.py file includes some test functions to help you test on your own before you submit to Gradescope. When you run your file, problems will be tested in order. If you wish to temporarily bypass specific tests (say, because you have not yet completed some functions), you can comment out individual test function calls at the bottom of your file in main(). However, be sure to uncomment and test everything together before you submit! Ask a CA if you need help with this.
Remember the course’s academic integrity policy. Solving the homework yourself is your best preparation for exams and quizzes; cheating or short-cutting your learning process in order to improve your homework score will actually hurt your course grade long-term.

Limitations

Do not use lists, list indexing, sets, dictionaries, recursion, or anything we have not yet covered in class or the notes. The autograder (or a manual CA review later) will reject your submission entirely if you do.

A Note About Style Grading

Starting with this assignment, we will be grading your code based on whether it follows the 15-112 style guide. We may deduct up to 10 points from your overall grade for style errors. We highly recommend that you try to write clean code with good style all along, rather than fixing your style issues at the end. Good style helps you code faster and with fewer bugs. It is totally worth it. In any case, style grading starts this week, so please use good style from now on!

A Note About Testing

You will notice that the skeleton file only includes testcases for some of the functions you are writing. You should write testcases for the others. (You can find some nice ways to test in the write-up below, but you will need to translate those to actual testcases.)

Problems

consonantCount(s) [5 pts]
Write the function consonantCount(s), that takes a string s, and returns the number of consonants in s, ignoring case, so "B" and "b" are both consonants. The consonants are all of the English letters except "a", "e", "i", "o", and "u". So, for example:
assert(consonantCount("Abc def!!! a? yzyzyz!") == 10)

rotateStringLeft(s, n) [5 pts]
Note: To receive credit, do not use loops on this problem.
Write the function rotateStringLeft(s, n) that takes a string s and a possibly-negative integer n. If n is non-negative, the function returns the string s rotated n places to the left. If n is negative, the function returns the string s rotated |n| places to the right. So, for example:
assert(rotateStringLeft('abcd', 1) == 'bcda') assert(rotateStringLeft('abcd', -1) == 'dabc')

isRotation(s, t) [10 pts]
Write the function isRotation(s, t) that takes two possibly-empty strings and returns True if one is a rotation of the other. Note that a string is not considered a rotation of itself.
Hint: rotateStringLeft may be helpful here.

topScorer [15 pts]
Write the function topScorer(data) that takes a multi-line string encoding scores as csv data for some kind of competition with players receiving scores, so each line has comma-separated values. The first value on each line is the name of the player (which you can assume has no integers in it), and each value after that is an individual score (which you can assume is a non-negative integer). You should add all the scores for that player, and then return the player with the highest total score. If there is a tie, return all the tied players in a comma-separated string with the names in the same order they appeared in the original data. If nobody wins (there is no data), return None (not the string "None"). So, for example:
data = '''\ Fred,10,20,30,40 Wilma,10,20,30 ''' assert(topScorer(data) == 'Fred') data = '''\ Fred,10,20,30 Wilma,10,20,30,40 ''' assert(topScorer(data) == 'Wilma') data = '''\ Fred,11,20,30 Wilma,10,20,30,1 ''' assert(topScorer(data) == 'Fred,Wilma') assert(topScorer('') == None)
Hint: you may want to use both splitlines() and split(',') here!

applyVigenereCipher(message, shift) [20 pts]
Background: As you have learned in CS Academy, a Caesar Cipher takes a message and a shift, and encodes each letter by shifting it by the given amount. We can strengthen this by changing the amount we shift each letter by. For example, say we have the message 'ABC' and we use the shifts 3,4,5. Then we shift 'A' by 3 to get 'D', we shift 'B' by 4 to get 'F', and we shift 'C' by 5 to get 'H'. So the encoded message is 'DFH'. Next, instead of listing the shifts as numbers, we can encode the shifts themselves in a string which we will call the key. Here, 'A' is 0, 'B' is 1, and so on. So the shifts 3,4,5 will be represented by the key 'DEF'. Finally, what happens if our key is shorter than our message? In that case, we will repeat the key until it is as long or longer than the message. For example, if we have the message 'FGHIJ' and the key 'AB', we first repeat the key to get 'ABABAB'. Now encode the message as just described with this key. A Vigenere Cipher works in this way. It takes a message and a key, repeats the key until it is at least as long as the message, and then uses the key to find the shift for each corresponding letter in the message. With this in mind, write the function applyVigenereCipher(msg, key) which returns the encoded message that results from perfoming a Vigenere Cipher on msg with the given key. Some notes:
- The message may be uppercase or lowercase. As usual, preserve the case when you shift letters.
- The key is always uppercase.
- The message can contain non-letter characters, and these are not shifted, so they appear in the result exactly as they did in the original message.
assert(applyVigenereCipher("FGHIJ", "AB") == "FHHJJ")

longestSubpalindrome [20 pts]
Complete the problem longestSubpalindrome(s) from CS Academy. You must solve the problem directly on the website, doing all of your testing there. Do not write the solution in Thonny (or a different IDE) and copy/paste it into the website.

patternedMessage(message, pattern) [25 pts]
Write the function patternedMessage(message, pattern) that takes two strings, a message and a pattern, and returns a string produced by replacing the non-whitespace characters in the pattern with the non-whitespace characters in the message (where any leading or trailing newlines in the pattern are first removed). As a first example:

call	result
patternedMessage("Go Pirates!!!", """ ************* ** ** ************* """)	GoPirates!!!GoP irates !!!GoP irates!!!GoPira

Here, the message is "Go Pirates!!!" and the pattern is a block of asterisks with a few missing in the middle. Notice how the whitespace in the pattern is preserved, but the whitespace in the message is removed. Again, note that any leading or trailing newlines in the pattern are removed.

Here is another example:

call	result
patternedMessage("Three Diamonds!",""" * * * * * * * * * * * * * * * """)	T h r eeD iam ond s!Thr eeDia monds !Th ree Dia m o n

Hint: While you may solve this how you wish, our sample solution did not use replace in any way. Instead, we started with the empty string, and built up the result character by character. How did we determine the next character? Using both the message and the pattern in some way...

And here is one last example, just for fun:

patternedMessage("Go Steelers!", """ oooo$$$$$$$$$$$$oooo oo$$$$$$$$$$$$$$$$$$$$$$$$o oo$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$o o$ $$ o$ o $ oo o$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$o $$ $$ $$o$ oo $ $ '$ o$$$$$$$$$ $$$$$$$$$$$$$ $$$$$$$$$o $$$o$$o$ '$$$$$$o$ o$$$$$$$$$ $$$$$$$$$$$ $$$$$$$$$$o $$$$$$$$ $$$$$$$ $$$$$$$$$$$ $$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$ $$$$$$$$$$$$$$ '$$$ '$$$'$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ '$$$ $$$ o$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ '$$$o o$$' $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$o $$$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$' '$$$$$$ooooo$$$$o o$$$oooo$$$$$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ o$$$$$$$$$$$$$$$$$ $$$$$$$$'$$$$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$' '''' $$$$ '$$$$$$$$$$$$$$$$$$$$$$$$$$$$' o$$$ '$$$o '$$$$$$$$$$$$$$$$$$'$$' $$$ $$$o '$$'$$$$$$' o$$$ $$$$o o$$$' '$$$$o o$$$$$$o'$$$$o o$$$$ '$$$$$oo '$$$$o$$$$$o o$$$$' '$$$$$oooo '$$$o$$$$$$$$$' '$$$$$$$oo $$$$$$$$$$ '$$$$$$$$$$$ $$$$$$$$$$$$ $$$$$$$$$$' '$$$' """)

Returns this:

                          GoSteelers!GoSteeler
                      s!GoSteelers!GoSteelers!GoS
                   teelers!GoSteelers!GoSteelers!GoS         te   el er
   s ! Go        Steelers!GoSteelers!GoSteelers!GoSteel       er s! GoSt
ee l e rs      !GoSteeler    s!GoSteelers!    GoSteelers       !GoSteel
ers!GoSte     elers!GoSt      eelers!GoSt      eelers!GoSt    eelers!G
  oSteele    rs!GoSteele      rs!GoSteele      rs!GoSteelers!GoSteeler
  s!GoSteelers!GoSteelers    !GoSteelers!G    oSteelers!GoSt  eele
   rs!GoSteelers!GoSteelers!GoSteelers!GoSteelers!GoSteel     ers!
    GoS   teelers!GoSteelers!GoSteelers!GoSteelers!GoSteelers     !GoSt
   eele   rs!GoSteelers!GoSteelers!GoSteelers!GoSteelers!GoSt       eele
   rs!    GoSteelers!GoSteelers!GoSteelers!GoSteelers!Go Steelers!GoSteele
  rs!GoSteelers  !GoSteelers!GoSteelers!GoSteelers!GoS   teelers!GoSteelers
  !GoSteelers!G   oSteelers!GoSteelers!GoSteelers!Go     Steel
 ers!       GoSt    eelers!GoSteelers!GoSteelers!G      oSte
            elers     !GoSteelers!GoSteelers!         GoS
              teel          ers!GoSteel           ers!
               GoSte                                elers
                !GoSte      elers!GoSteele        rs!Go
                  Steelers     !GoSteelers!   GoStee
                     lers!GoSte  elers!GoSteeler
                        s!GoSteele rs!GoSteel
                                ers!GoSteele
                                    rs!GoSteeler
                                     s!GoSteeler
                                      s!GoS